It is recognized that the thorough cleaning of deep pile carpets or shag rugs is exceedingly difficult. Since a conventional vacuum cleaning tool cannot penetrate deeply enough in the carpet to remove the dirt and dust particles that are present between and below the fibres of the pile, several attempts have been made to devise and construct a vacuum cleaner tool for cleaning this type of floor covering. One known construction placed a combing device ahead of a conventional vacuum cleaner nozzle in order to improve the dust and dirt pick up capability of the tool. The object of this known construction is to raise the pile of the rug or carpet a sufficient amount to enable the vacuum cleaner nozzle to come close to and clean the bottom area of the carpet. However, this type of tool has proved to be cumbersome, and therefore difficult to handle and, most important, the cleaning result did not prove to be satisfactory.
Another known type of vacuum cleaner tool specifically designed for use on deep pile rugs is described in U.S. Pat. No. 3,733,640 in which a structure is shown having a wire element for contact with the work surface. This structure is arranged to surround an elongated suction opening extending along the entire length of the tool. As this tool is used, the carpet pile is combed by the wire element. However, this tool does not improve the dust pick-up capability over the other known structures, and this generally is due to the form of the suction opening of the tool, and also to the comparatively great distance between the suction opening and the surface to be worked on.
Another type of vacuum cleaner tool is shown and described in U.S. Pat. No. 3,745,603 to Bayless et al, in which a number of suction nozzles are disclosed which project from the tool housing. The nozzles are of such a form that in addition to removing dust and dirt, they comb the carpet pile, thus somewhat improving the removal of the dust and dirt particles from the rug. The cleaning result is better than the other aforementioned suction nozzle, but because of the enlarged area of the intake opening of the suction nozzle the air velocity is quite low near the surface of contact with the carpet, which therefore negatively influences the dust and dirt removing capabilities of the vacuum cleaner tool. Furthermore, the comparatively large width of the nozzles causes part of the carpet pile to be flattened underneath the nozzle instead of being caused to stand up in a substantially vertical plane so that dirt and dust will remain in the carpet and will not be picked up by the tool.